1. Field of the Invention
The present invention relates to a film winding/rewinding device capable of being driven by a single built-in motor for both winding the film and rewinding the film.
2. Description of the Related Art
A conventional film winding/rewinding device for a camera, in general, is provided with a transmission mechanism comprising a train of a plurality of spur gears to drive a film winding spool and a rewinding fork.
Referring to FIG. 3 showing a typical film winding/rewinding device, a motor 101 is placed in a hollow film winding spool 121, and a transmission gearing is formed on the bottom wall of the camera body. The transmission gearing comprises a pinion 103 fixed to the output shaft 102 of the motor 101, a train of spur gears 104 to 108, a clutch CL comprising a swing plate 110 and gears 109 and 111, and a train of spur gears 112 to 116. A spur gear 108b coaxial with the spur gear 108 is in mesh with a spur gear 125 formed at one end of the film winding spool 121 to drive the film winding spool 121. The spur gear 116 is fixed to a rewinding fork 117 with which the shaft of a film cartridge engages.
When winding the film, the output shaft 102 of the motor 101 is rotated in the normal direction, i.e., a film winding direction, and the gear 109 rotates in the film winding direction. Then, the swing plate 110 of the clutch CL is turned in the direction of the arrow a about the axis of the gear 109 to disengage the gear 111 from the gear 112. Consequently, the rewinding fork 117 is disconnected from the motor 101 and only the film winding spool 121 is driven to wind the film. When rewinding the film, the output shaft 102 of the motor 101 is rotated in the reverse direction, i.e., a film rewinding direction. Then, the swing plate 110 of the clutch CL is returned to a position shown in FIG. 3 to bring the gear 111 into engagement with the gear 112, so that power is transmitted to the rewinding fork 117 for rewinding operation. During the rewinding operation, the film winding spool 121 is rotated in the reverse direction to loosen the film tightly wound on the film winding spool 121.
With recent increasing request for the miniaturization and weight reduction of the camera, a new film winding/rewinding device has been required, because the conventional film winding/rewinding device comprising a train of spur gears needs a comparatively large number of parts which is disadvantageous for the miniaturization and weight reduction of the camera.
Furthermore, recent development of magnetic materials and improvements in the construction of the motor have enabled the development of a miniaturized motor far smaller than the conventional motor and capable of being placed within the film winding spool and the effective use of the internal space of the camera body. However, since the length of the motor is small as compared with the length of the film winding spool, an unutilized space, such as vacant space 122 shown in FIG. 3, remains in the limited internal space of the camera body. When the motor is placed within the film winding spool, the outside diameter of the motor is limited by the inside diameter of the film winding spool and hence only limited motors are available.